text: /*
     linear.c : Multiple Devices driver for Linux
  	      Copyright (C) 1994-96 Marc ZYNGIER
  	      <zyngier@ufr-info-p7.ibp.fr> or
  	      <maz@gloups.fdn.fr>
  
     Linear mode management functions.
  
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; either version 2, or (at your option)
     any later version.
  
     You should have received a copy of the GNU General Public License
     (for example /usr/src/linux/COPYING); if not, write to the Free
     Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
  
  #include <linux/blkdev.h>
  #include <linux/raid/md_u.h>
  #include <linux/seq_file.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include "md.h"
  #include "linear.h"
  
  /*
   * find which device holds a particular offset
   */
  static inline struct dev_info *which_dev(struct mddev *mddev, sector_t sector)
  {
  	int lo, mid, hi;
  	struct linear_conf *conf;
  
  	lo = 0;
  	hi = mddev->raid_disks - 1;
  	conf = mddev->private;
  
  	/*
  	 * Binary Search
  	 */
  
  	while (hi > lo) {
  
  		mid = (hi + lo) / 2;
  		if (sector < conf->disks[mid].end_sector)
  			hi = mid;
  		else
  			lo = mid + 1;
  	}
  
  	return conf->disks + lo;
  }
  
  static int linear_congested(struct mddev *mddev, int bits)
  {
  	struct linear_conf *conf;
  	int i, ret = 0;
  
  	conf = mddev->private;
  
  	for (i = 0; i < mddev->raid_disks && !ret ; i++) {
  		struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);
  		ret |= bdi_congested(&q->backing_dev_info, bits);
  	}
  
  	return ret;
  }
  
  static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks)
  {
  	struct linear_conf *conf;
  	sector_t array_sectors;
  
  	conf = mddev->private;
  	WARN_ONCE(sectors || raid_disks,
  		  "%s does not support generic reshape\n", __func__);
  	array_sectors = conf->array_sectors;
  
  	return array_sectors;
  }
  
  static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
  {
  	struct linear_conf *conf;
  	struct md_rdev *rdev;
  	int i, cnt;
  	bool discard_supported = false;
  
  	conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),
  			GFP_KERNEL);
  	if (!conf)
  		return NULL;
  
  	cnt = 0;
  	conf->array_sectors = 0;
  
  	rdev_for_each(rdev, mddev) {
  		int j = rdev->raid_disk;
  		struct dev_info *disk = conf->disks + j;
  		sector_t sectors;
  
  		if (j < 0 || j >= raid_disks || disk->rdev) {
  			printk(KERN_ERR "md/linear:%s: disk numbering problem. Aborting!\n",
  			       mdname(mddev));
  			goto out;
  		}
  
  		disk->rdev = rdev;
  		if (mddev->chunk_sectors) {
  			sectors = rdev->sectors;
  			sector_div(sectors, mddev->chunk_sectors);
  			rdev->sectors = sectors * mddev->chunk_sectors;
  		}
  
  		disk_stack_limits(mddev->gendisk, rdev->bdev,
  				  rdev->data_offset << 9);
  
  		conf->array_sectors += rdev->sectors;
  		cnt++;
  
  		if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
  			discard_supported = true;
  	}
  	if (cnt != raid_disks) {
  		printk(KERN_ERR "md/linear:%s: not enough drives present. Aborting!\n",
  		       mdname(mddev));
  		goto out;
  	}
  
  	if (!discard_supported)
  		queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
  	else
  		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
  
  	/*
  	 * Here we calculate the device offsets.
  	 */
  	conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
  
  	for (i = 1; i < raid_disks; i++)
  		conf->disks[i].end_sector =
  			conf->disks[i-1].end_sector +
  			conf->disks[i].rdev->sectors;
  
  	return conf;
  
  out:
  	kfree(conf);
  	return NULL;
  }
  
  static int linear_run (struct mddev *mddev)
  {
  	struct linear_conf *conf;
  	int ret;
  
  	if (md_check_no_bitmap(mddev))
  		return -EINVAL;
  	conf = linear_conf(mddev, mddev->raid_disks);
  
  	if (!conf)
  		return 1;
  	mddev->private = conf;
  	md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
  
  	ret =  md_integrity_register(mddev);
  	if (ret) {
  		kfree(conf);
  		mddev->private = NULL;
  	}
  	return ret;
  }
  
  static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
  {
  	/* Adding a drive to a linear array allows the array to grow.
  	 * It is permitted if the new drive has a matching superblock
  	 * already on it, with raid_disk equal to raid_disks.
  	 * It is achieved by creating a new linear_private_data structure
  	 * and swapping it in in-place of the current one.
  	 * The current one is never freed until the array is stopped.
  	 * This avoids races.
  	 */
  	struct linear_conf *newconf, *oldconf;
  
  	if (rdev->saved_raid_disk != mddev->raid_disks)
  		return -EINVAL;
  
  	rdev->raid_disk = rdev->saved_raid_disk;
  	rdev->saved_raid_disk = -1;
  
  	newconf = linear_conf(mddev,mddev->raid_disks+1);
  
  	if (!newconf)
  		return -ENOMEM;
  
  	mddev_suspend(mddev);
  	oldconf = mddev->private;
  	mddev->raid_disks++;
  	mddev->private = newconf;
  	md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
  	set_capacity(mddev->gendisk, mddev->array_sectors);
  	mddev_resume(mddev);
  	revalidate_disk(mddev->gendisk);
  	kfree(oldconf);
  	return 0;
  }
  
  static void linear_free(struct mddev *mddev, void *priv)
  {
  	struct linear_conf *conf = priv;
  
  	kfree(conf);
  }
  
  static void linear_make_request(struct mddev *mddev, struct bio *bio)
  {
  	char b[BDEVNAME_SIZE];
  	struct dev_info *tmp_dev;
  	struct bio *split;
  	sector_t start_sector, end_sector, data_offset;
  
  	if (unlikely(bio->bi_rw & REQ_FLUSH)) {
  		md_flush_request(mddev, bio);
  		return;
  	}
  
  	do {
  		tmp_dev = which_dev(mddev, bio->bi_iter.bi_sector);
  		start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
  		end_sector = tmp_dev->end_sector;
  		data_offset = tmp_dev->rdev->data_offset;
  		bio->bi_bdev = tmp_dev->rdev->bdev;
  
  		if (unlikely(bio->bi_iter.bi_sector >= end_sector ||
  			     bio->bi_iter.bi_sector < start_sector))
  			goto out_of_bounds;
  
  		if (unlikely(bio_end_sector(bio) > end_sector)) {
  			/* This bio crosses a device boundary, so we have to
  			 * split it.
  			 */
  			split = bio_split(bio, end_sector -
  					  bio->bi_iter.bi_sector,
  					  GFP_NOIO, fs_bio_set);
  			bio_chain(split, bio);
  		} else {
  			split = bio;
  		}
  
  		split->bi_iter.bi_sector = split->bi_iter.bi_sector -
  			start_sector + data_offset;
  
  		if (unlikely((split->bi_rw & REQ_DISCARD) &&
  			 !blk_queue_discard(bdev_get_queue(split->bi_bdev)))) {
  			/* Just ignore it */
  			bio_endio(split);
  		} else
  			generic_make_request(split);
  	} while (split != bio);
  	return;
  
  out_of_bounds:
  	printk(KERN_ERR
  	       "md/linear:%s: make_request: Sector %llu out of bounds on "
  	       "dev %s: %llu sectors, offset %llu\n",
  	       mdname(mddev),
  	       (unsigned long long)bio->bi_iter.bi_sector,
  	       bdevname(tmp_dev->rdev->bdev, b),
  	       (unsigned long long)tmp_dev->rdev->sectors,
  	       (unsigned long long)start_sector);
  	bio_io_error(bio);
  }
  
  static void linear_status (struct seq_file *seq, struct mddev *mddev)
  {
  
  	seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
  }
  
  static void linear_quiesce(struct mddev *mddev, int state)
  {
  }
  
  static struct md_personality linear_personality =
  {
  	.name		= "linear",
  	.level		= LEVEL_LINEAR,
  	.owner		= THIS_MODULE,
  	.make_request	= linear_make_request,
  	.run		= linear_run,
  	.free		= linear_free,
  	.status		= linear_status,
  	.hot_add_disk	= linear_add,
  	.size		= linear_size,
  	.quiesce	= linear_quiesce,
  	.congested	= linear_congested,
  };
  
  static int __init linear_init (void)
  {
  	return register_md_personality (&linear_personality);
  }
  
  static void linear_exit (void)
  {
  	unregister_md_personality (&linear_personality);
  }
  
  module_init(linear_init);
  module_exit(linear_exit);
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Linear device concatenation personality for MD");
  MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
  MODULE_ALIAS("md-linear");
  MODULE_ALIAS("md-level--1");
  